The present invention generally concerns sliding elevator doors and, in particular, a runner guide for quiet operation of such a door.
It is known that sliding door runners having rollers with metallic running surfaces traveling on metallic guide rails cause disturbing noises. For this reason, different kinds of non-metallic running surfaces for runners were created, which surfaces help to reduce the running noises. The softer the nature of the running surface, the less running noise is generated. On the other hand, the rolling resistance increases for softer materials, which resistance can, however, be compensated for by correspondingly increased door driving power.
The phenomenon of the running surface flattening at standstill has an appreciably worse effect, because a bump motion with corresponding cluttering noises is the consequence thereof. The flat spots are created when a loaded roller remains standing in the same position for a long time. This operation applies particularly to the automatic sliding elevator door, since these doors must regularly remain in the closed position for several hours.
A good solution which does not have the above identified disadvantages and nevertheless promises quiet
is described in the U.S. Pat. No. 2,611.920. The roller has a vibration-damping intermediate layer positioned between an outer ball bearing ring and a roller body, and the roller guide rail likewise displays such a layer between its foot portion and an upper portion. A flattening of the running surface cannot take place, but the running operation is not as quiet as desired. In spite of the vibration-damping intermediate layers in the roller and in the guide rail, a metal-on-metal rolling friction always is present. Moreover, the construction is very expensive, whereby the additional costs tend not to be justifiable for this application.